/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/Widgets/SItemSelector.h
An optional delegate which determines the sorting for categories. If not bound categories will be ordered by the order they're encountered while processing items.
WidgetArgsType & OnCompareCategoriesForSorting &40; const FOnCompareCategoriesForSorting & InDelegate &41;